The instant invention is concerned with a volumetric fluid flow sensing system of a type having a pole magnet armature in which the direction of reciprocation of the armature is co-linear with the magnetic axis thereof. Such a system is further provided with a magnetic field sensor which is in magnetic communication with said magnetic axis. Changes in the field strength of said magnetic axis in the vicinity of said field sensor are monitored to thereby provide an electrical signal which is proportional to changes in volumetric fluid flow passing through an inlet channel and annularly about the pole magnet armature and to an outlet channel of the system.
The prior art includes U.S. Pat. No. 3,759,099 (1973) to McGregor, entitled Flow Meter; and U.S. Pat. No. 4,507,976 (1975) to Banko, entitled Flow Meter with Hall Effect Sensor and Method. However these, and other art known to the inventor, do not involve the use of a magnetic field sensor to measure changes in magnetic flux density of the magnetic axis of the magnetic armature in combination with the control of certain other system variables, these variables including the cross-section of a fluid interface between the fluid inlet channel and fluid outlet channel, modification of the cross-sectional geometry of one or more portions of the path of fluid flow from said inlet to said outlet channel; modification of the geometry, mass or magnetic flux characteristic of the pole magnet armature; or change in the axial location, relative to the axis of the pole magnet armature, of a calibration magnet. Change of any of the variables will affect the actuating characteristic of the armature and thereby of the sensor system.
The underlying importance of the present sensing system resides in the provision of an efficient and economical means for effecting changes in ranges of volumetric fluid flow measurements which, heretofore, could only be achieved through the use of more complex equipment involving substantially greater cost than is the case in the fluid flow sensing system described herein.